The invention concerns an implantable stent which is insertable as a support sleeve in the region of a vascular constriction, especially of the type expanded by a balloon catheter, whereby the stent is expandable radially and is open or broken continuously along at least one longitudinal side or meridian line.
Such a stent is known from EP 0 246 998 A2. Here in the initial position the edges on the open longitudinal side overlap and the stent can only be expanded in that this overlapping is diminished. This takes place against the elastic restoring forces of the material of the stent, and on the one longitudinal edge, grooves are provided into which the other longitudinal edge can be pressed in at all times under the material tension and the pressure of the vessel wall. This means on the one hand a relatively expensive manufacture and on the other hand only a relatively minor expandability. Furthermore, the expansion must take place very precisely so that the one longitudinal edge can in any given case engage in the internal longitudinal grooves of the other longitudinal edge. Finally, only step-wise expanasions are possible, whereby the steps correspond to the spacings of the internal longitudinal grooves.
In addition, stents made with perforations about their periphery which is made of metal are known. These have a web or meandering structure such that a radial expansion is possible through appropriate deformations. Such stents which resemble a wire cage which can be expanded in the vessels themselves are implanted, for example, in infants with congenital heart defects or, also in many cases with adults. A previously unsolved problem consists in that a subsequent, if need be repeated reexpansion, that is, an enlargement of the periphery of the stent or support sleeve, for example, conditioned by growth in children, is not possible after a certain expansion stage. The consequence of this is that, due to the stent, an artificial constriction of the vessel can subsequently take place.